from mininet.topo import Topo

class MyTopo(Topo):

    def __init__(self):

        # initilaize topology
        Topo.__init__(self)

        # add hosts
        h1 = self.addHost('h1')
        h2 = self.addHost('h2')
        h3 = self.addHost('h3')
        h4 = self.addHost('h4')
        
        # add switches
        s1 = self.addSwitch('s1')
        s2 = self.addSwitch('s2')
        
        # add links
        self.addLink(h1, s1, 1, 1)
        self.addLink(h2, s1, 1, 2)
        self.addLink(h3, s2, 1, 1)
        self.addLink(h4, s2, 1, 2)
        self.addLink(s1, s2, 3, 3)
topos = {'mytopo': (lambda: MyTopo())}

